[seqfan] Numbers n such that the decimal representation of n is contained as substring in that of the n-th pentagonal number.
jvospost3 at gmail.com
Tue Jul 27 02:45:24 CEST 2010
Before I submit this, as I've made errors in some recent submissions,
would anyone like to code it, and verify, correct, or extend it?
%S A000001 0,1,5,7,25,67,482
%N A000001 Numbers n such that the decimal representation of n is
contained as substring in that of the n-th pentagonal number.
%C A000001 This is to pentagonal numbers A000326 as A119238 is to
triangular numbers A000217 and as A018834 is to squares A000290.
%e A000001 The 5th pentagonal number, 35, which contains 5.
%e A000001 The 7th pentagonal number, 70, which contains 7.
%e A000001 The 25th pentagonal number, 925, which contains 25.
%e A000001 The 67th pentagonal number, 6700, which contains 67.
%e A000001 The 482nd pentagonal number, 348245, which contains 482.
%Y A000001 Cf. A000217, A000290, A000326, A018834, A119238.
%K A000001 base,more,nonn
%O A000001 1,3
%A A000001 Jonathan Vos Post (jvospost3(AT)gmail.com), Jul 26 2010
I presume it interesting, as "base" sequences go, because it is the
analog of at least two exisiting sequences, and thus part of a larger
I'd prefer to be sure of this for 5-gonal numbers, as well as for
existing analog in 3-gonal and 4-gonal numbers, before going to more
elaborate sequences for k-gonal number with k>5.
Jonathan Vos Post
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